Stilbene dye and process of producing the same



Patented Sept. 20, 1932 a U irEn v STATES Parent mic-e onauncnx ALLAN LYFOEZD, or iiasm- AURORA, NEW roan; nssrenon. ro NATIonA-n ANILINE & CHEMICAL COMPANY,'II\TG., on EW YORK, n. Y., A oonroRA'rIoN on NEW YORK STILIBENE DYE AND PROCESS OF PRODUCING THE SAME Ho Drawing.

This invention relates to the preparation of dyestuffs derived from stilbene (diphenylethylene) It relates particularly to improvements in the manufacture of stilbene azo dyestuffs by the reduction of tAJ-dinitrostilbene- 2.2-disulfonic acid in an alkaline medium, said improvements comprising the employment as reducing agent of an aldehyde having the formula ECHO (in which Rrepresents hydrogen, a non-hydroxylic aliphatic hydrocarbon radical, or a furfuryl radical). The

under varying conditions of concentration I and temperature (cf. U! S. Patent No. 360,-

553). In accordance with the; otherfmethod, 4.4-dinitro stilbene-2.2-disulfon1c acid is treated with a reducing agent,fsuch;as, gluamounts of other products, such as, diamino stilbene-disulfonic acid." These azo derivatives have, respectively, the probable fonmt;

l'as:

SOaHV 303K Application filed February 1, 1929. Serial no. 336.924..

7 on=on 03H soan 0511 (Colour Index No 620) I V and V Qo11=orr soar I soaH' (Colour Index No. 621).

The more ofthe dinitro-d erivative there is present in the dye,the greener the shade of the dyeing made therewith; and the more of the 'disazoederivative there is-present, the

has heretotorebeen proposed to reduce di-.

nitrostilbene-disulfonic acid with a mini mum amount of glucose, ,whereby only a part of thedinitro stilbene-disulfonic acid is reduced and low yields of dyestuffare obtained. Owing to the vigorous reducing action of the glucose,contaminating higher reduction products are also produced 3 even when the minimum amount of glucose is employed. In order-to obtain dyestuffs giving the redder shades, it has been proposed to carryout the reduction under more drastic conditions, whereby diamino stilbene and other over-reduction products are formed, decreasing the purity and the yield of dyestufi.

One of the objects of the invention is the production of dyestuffs from dinitro stilbenedisulfonic acid in increased yield.

Another object of the invention is an improvement in the process of producing dyestuifs from dinitro stilbene-disulfonic acid whereby the shade. of the resulting dyestutf can be controlled without deleteriously affecting the yield of dyestufi.

Another object of the invention is an improvement in the process ofproducing dyestuifs from dinitro stilbene-disulfonic acid whereby not only are products obtained which give dyeings of bright shade, but they are obtained in good yield.

Another object of the invention is the production of a yellow stilbene dye which dyes cotton greener and brighter shades than the yellow stilbene dyes formerly produced, which dyes paper brightgreenish-yellow shades, and which forms with barium chlo-' ride and basic aluminum hydroxide brigh greenish yellow, clear color-lakes.

- These and other objects of the invention will be apparent from a consideration of the following disclosure whichis given for the purpose of illustrating the invention.

The present invention is based upon the discovery that if in the production of a stil bene dyestuif by the alkaline reduction of LF-dinitro stilbene-22-disulfonic acid there is employed a reducing agent comprising'an aldehyde having the formula ECHO (in which R represents hydrogen, a non-hydroxylic aliphatic hydrocarbon radical, or a furfuryl radical), particularly, formaldehyde, the process can be more readily controlled, and dyestufis of .a bright shade can be obtained in yields that are greater than those formerly obtained.

Inv carrying out theprocessin accordance Y with the presentv invention, 4.a-dinitro stilbene-2.2 ,disulfonic acid jis treated in an aqueous caustic alkali solution with a solu tion of an aldehyde of the above type (for example, formaldehyde, acetaldehyde, fur-fural, or equivalent aldehyde), more particularly, a non-hydroxylic aliphatic aldehyde, and specifically, formaldehyde. By varying the concentration of the alkali, the reaction temperature, and the quantity vof aldehyde,

dyestuffs can be obtained which vary in color from greenish-yellow tored, wh ch dissolve in concentrated sulfuric acid forming solutlons rang ng in color from orange-yellow to red to purple, and which dye cotton from a neutralsalt bath greenish-yellow to orange shades. For example, by heating 1 mol of lAU-dinitro stilbene-22f-disulfonic acidjin an aqueous caustic alkali solution,'containing about 5 to 6 mol s of caustic alkali, with about at mols of a non-hydroxylic aliphatic aldehyde, such as, formaldehyde, at a tem perature of about 7 0 (1, a dyestuff which dyes cotton greenish-yellow shades can be ob tained in relatively high yield.

By increasing the extent of the reduction, for example, by increasing the quantity of alkali, and/or by operating under more elevated temperature conditions, and/ or by increasing the quantity of the aldehyde, dyestuffs can be obtained which give dyeings of redder shades. Thus, in the above reduction, if about 7 mole of formaldehyde and about 10 mols of caustic alkali are employed, a dyestuif which dyes cotton orange shades can be obtained in relatively high yield with formation of a relatively small amount, if any, of over-reduction products.

The invention will be further described in connection with the following specific examples which are givenfor the purpose of illustration. The parts are by weight.

Example 1.p'arts of 4.4-dinitro stilbene-2.2-disulfonic acid disodium salt, in the form of a 50 per cent paste with water, is suspended with agitation in 500 parts of water. The suspension is heated to 50" C.- whereby a clear yellowish solution forms. While continuing the agitation there is added parts .of a 47 B. sodium hydroxide solution (containing about 30 parts of NaOH) and thejagitation is further continued until a homogeneous, light yellow colored, creamy paste results. Thetemperature spontaneously rises to about 5657 C. If the temperature does notrise to about 57? 0., the mixture is brought to that temperature, and 48.7 parts ofa 37 per cent formaldehyde solution (containing about 16 parts HCHO is added in small portions, theaddition being so regu lated as to require from" about 12 to about 15 minutes for its completion. During the additionof the formaldehyde the temperature rises to about 0., the reaction mixture forms a deeporange colored solution, and the resulting dyestuifcommences to crystallize out; After the addition of the formaldehyde, agitation iscontinued for an ad ditional period of about 3 hours, the temperature bein allowed gradually to drop to about 6062 By this time the dyestuff should be completely crystallized, as shown by spot-: ting upon filter paper. 50 Be. sulfuricacid is then added to the batch until; neutral to brilliant yellow and Congo papers, about 38.5 parts of said acid ordinarily being re-; quired. The temperature rises to about 70 C. and the batch is agitated until it falls to about 55 C; at whichpoint-the mixture is filteredon a suction filter. The dyestulf is driedin theair at a temperature of about 80 to 90 C., and ground to a powder. The powderobtained is of a bright red color, is soluble in concentrated sulfuric acid with an orange color,;and dyes cottondirectly in bright yellow shades.

EmmpZe Z.Dinitro stilbene-disulfonic acid disodium salt is treated according to the method of- Example 1, with the difference that instead of 65 parts of 47 Be. caustic soda solution and 4:3.7-partsof a 37 per cent solu-tion'of formaldehyde there are used 58 parts of a 47 B. sodium hydroxide so'lution and about 80 to 38, preferably about 35, parts of a 37 percent solution of formaldehyde. Thedyestuff thereby obtained, which is of a greener shade of yellow than that of Example 1,- appears to be a new product inasmuch as it gives dyeings on cotton of a greener, and brighter shade than do those stilbene dyestuffs hitherto produced by the reduction of dinitro stilbene-disulfonic acid. It dissolves in concentrated sulfuric" acid with a yellowish-orange coloration, dyes paper bright greenish-yellow shades, and forms with barium chloride and basic aluminum hydroxide clear and bright greenish-yellow color-lakes. Y n l It will be understood that the invention is not limited to theabove examples. Thus,

1 the quantity of formaldehyde may be varied from about 0.5 to about 1.25 partsof formaldehyde solution per part of dinitrostilbene-disulfonic acid disodium'salt, or from about?) to about 8 mols of formaldehyde per mol of dinitro stilbene-disulfonic acid disodium salt; and in the preparation of the new'dye'stuff of Example 2, the formaldehyde may vary in amount from about 3 to about 3,7; mols of formaldehyde per mol of dinitro stilbene disulfon-ic acid; Instead of formal dehyde, there may be used equivalent proportions of other aldehydes which conform with the formula ECHO, wherein R is a non-hy-- droxylic aliphatic hydrocarbon radical (such as, CH C l-l etc.) or a furfuryl radical; specifically, acetaldehydeor furfural, The amount of caustic-alkali employed may also vary; Although about'5 to about 1O. mols ofsod-ium hydroxide permol of dinitro stilbene-disulfonic acid disodium salt is' preferred, the minimum amount that generally may be employed is that quantity necessary both to produce sodium formate with the formaldehyde present and to provide a sufli ciently concentrated sodium hydroxide solution to enable the condensation reaction to occur. Instead of a 47 Be. sodium hydroxide solution and a 87 per centformaldehyde solution, proportionate quantities of solutions of other strengths may be used. The temperature of the reaction may be varied from about 50 to about 90 ,C., and is preferably maintained between about to about C. Other mineral acids besides sulfuric acid may be used inneutralizing the reaction mixture, such as, hydrochloric acid; and the strength of said mineral acid may vary, as will be readily understood. The dye-stuff is preferably filtered at above about 50 C.

l when sulfuric acid has been used to neutralize stuff and, without danger of the excess caustic, in order to avoid the preas upon the temperature of the reaction; a

more "concentratedaldehyde, a more conc'entrated sodium hydroxide solution, and a highertemperature causing a greater degree ofreduction and consequently a redder shade; The dyestuffs obtained in accordance with this invention may be used for the direct dyeing of cotton and paper in greenish-yellow to orange shades, and for the production ofclear greenish-yellow to orange color lakes by precipitationo'fsaid dyestuffs with barium chloride upon basic aluminum hydroxide.

The process of this invention'as above described is easily controlled and enables the production of stilbene azo dyes-of the desired shad-e without a decrease of the yield of dyeover-reduction. 'I' claim V *1. .In jthe production of a stilbene dyestufl' by a process comprising the reduction-of 4.4" dinitrostilbene-22'-disulfonic acid in an alkaline medium, the improvement which comprises reducing 4c.4="-din-itr'o stilbene-2.2- disulfonic acid .with'an aldehyde having the formula ECHO, wherein R represents hydrogen, a non-hydroxylic aliphatic hydrocarbon radical, or a furfuryl radical.

2. Inthe production of a'stilbenedyestuif V by a process comprising the reduction of4.4-'

dinitro stilbene-2.2 disulfonic acid in an alkaline medium, the improvement which comprises jreducing t ff-dinitrostilbene-2.2-disulfonic acid with a non-hydroxylicaliphati aldehyde. 1 1 v 3 Inthe production of a stilbene dyestufi' by a process comprising the reduction of 4.4 dinitro stilbene-2.2-disulfonic acid in an alkaline medium, the improvement'whi'ch com prises reducing" 4.4-dinitro stilbene-2.2 -di sulfonic acid with formaldehyde,

4. In the production of a stilbene dyestuif bya process comprising the reduction of 4.4- dinitro stilbene-2.2-disulfonic acid in a caustic alkali medium, the improvement which comprises reducing Ly-dinitro stilbene-2.2

disulfonio acid with an aldehyde having the formula ECHO, wherein R represents'hy droge'n, a" non-hydroxylic' aliphatic hydrocarbon radical, or a' furfuryl radical, at a temperature of about50 to about C. 5. 111 the production of a stilbene' dyes-tuif by a process comprising the reduction of 4.4-

dinitro stilbene-2.2 disulfonic ''acid in a V caustic alkali medium,- the" improvement" 1,

which comprises reducing 4.4;. dinitro sstilbene 2.2-disulfonic acid with a non-hyd-roxylic aliphatic aldehyde, at a temperature vof about to about 90 C.

6. In the production of a stilbene dyestufi by a process comprising thereductionof-aa dinitro stilbene-2.2-disulfonic acid ,in a caustic alkali medium, thev improvement which comprises reducing 4 .4-dinitro stilbene-2.2v-disulfonic acid with formaldehyde, at a temperature of'about 50 to about 90 (3. 7 In the production ofv a stilbene dyestufi' by aprocesscomprisingrthe reduction of4.4-

dinitro stilbene-2.2?-disulfonic acid in an al- 8 mols of aldehyde 'kaline medium, the improvement which comprisesheatingtA dinitro stilbene-2,2-disulfonic acid with caustic alkaliand an aldehyde having the formula ECHO, wherein R represents hydrogen, a non-hydroxylic ali-, phatic hydrocarbon radical, or a furfuryl radical, in the proportion-of about 3 toabout per molof dinitro stilbene-disulfonic acid.

; 8. In the production of a stilbene dyestufi by a process comprising the reduction of- 41.42 fdil1lf/I'O stilbene-2.2 disulfonic acid in an alkaline medium, the improvement which comprises heating eat-dinitro stilbene-2.2: disulfonic acid with caustic alkali and with a non-hydroxylic aliphatic aldehyde in the proportion of about 3 to about 8 mols'of aldehycclle per mol ofdinitrostilbene-disulfonic acr v 9. In the production of a. stilbene dyestuff by a process comprising thereduction of 4.4 dinitro stilbene-2.2 disulfonic acid in an alkaline medium, the improvement Whichcomaqueous caustic alkali and with an aldehyde prises heating 4.L-dinitro stilbene-2.2-disulfonic acid with caustic alkali and with formaldehyde in the proportion of about 3 to about 8 mols of formaldehyde per mol of dinitro stilbene-disulfonic acid. 3

10. In theproduction ofa stilbene dyestuff byva process comprising the reduction of i AJ-dinitro stilbene-2.2-disulfonic acid, the

improvement which comprises heating 4,4- dinitro stilbenee22f-disulfonic acid with having the formulaRCHO, wherein-R represents hydrogema non-hydroxylic aliphatic hydrocarbon radical, or a'furfuryl=radical,'in the proportion ofabout 3 to about 8 mols of aldehyde per mol of dinitro stilbene-disulfonic acid, ata temperatureof about 50 to about 75 C. r r

11. In the production of a stilbene, dyecolor-lakes.

12. The process of producing a stilbene dyestuff which comprises heating Aedinitro stilbene-2.2-disulfonic acid with an aqueous sodium hydroxide solution and with a nonhydroxylic aliphatic aldehyde in the proportion of about 3 :to about 3.7 mols of aldehyde per mol of dinitro stilbene-disulfonic acid, at a temperature of about 50 to about 75 C.

13. The, process of producing a stilbene dyestuff which comprises heating aAF-dinitro stilbene-2.2-disulfonic acid with an aqueous sodium hydroxide solution and formaldehyde in the proportions of about 5 to about 6 mols of sodium hydroxide and about 3 ,to-

and formingwith barium chloride and basic aluminum hydroxide clear greenish -yellow 15. A stilbene dye obtained by reducing m ttdinitro stilbene-2.2-disulfonic acid in an alkaline medium with a non-hydroxylic aliphatic aldehyde, said dye being a greenish yellow to -redpowder, dissolving in concentrated sulfuric acid with an orange yellow to red coloration dyeing cotton from a neu- Ttral saltbath bright greenish yellow ,to orange shades, and forming with barium. chloride and basic aluminum hydroxide clear greenish yellow to orange color. lakes.

In testimony whereof I afiix my signature.

. CHAUNGEY ALLAN LYEORD.

stuffbya process comprising the reduction of I lj-din-itro stil'bene-2.2edisulfonic acid, the

improvement which comprises heating i.4'- V dinitro ;stilbene-2.21disulfonic acid 'with aqueous causticalkali and with formaldehyde in the proportion of aboutBto about 8 0 mols of formaldehyde perlmol of dinitro stilbene-disu'lfonic acid, ata temperature of aboutfiO" tpa ut 5C. o 

